Assessing future climatic changes of rainfall extremes at small spatio-temporal scales

Gregersen, Ida Bülow; Sørup, Hjalte Jomo Danielsen; Madsen, Henrik; Rosbjerg, Dan; Mikkelsen, Peter Steen; Arnbjerg‐Nielsen, Karsten

doi:10.1007/s10584-012-0669-0

Cited by 70 publications

(94 citation statements)

References 24 publications

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“…A dry weather period of one day is required for two succeeding events to be considered as independent (Gregersen et al 2013b;Madsen et al 2002). For consistency with previous Danish studies (Gregersen et al 2013b;Madsen et al 2002) we apply a threshold which yields approximately three extreme events per year in the standard normal period of 1961-1990. Due to the highly variable nature of rainfall extremes it can be difficult to separate long term trends from random variations, when the evaluations are made on an annual basis. Ntegeka and Willems (2008) successfully applied a moving window of 5-15 years as a filter to enhance the multidecadal signal for extreme rainfall variations.…”

Section: Perturbation Factors For Extreme Rainfallmentioning

confidence: 99%

Long term variations of extreme rainfall in Denmark and southern Sweden

Gregersen

Madsen²,

Rosbjerg

et al. 2014

Clim Dyn

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Section: Perturbation Factors For Extreme Rainfallmentioning

confidence: 99%

Long term variations of extreme rainfall in Denmark and southern Sweden

Gregersen

Madsen²,

Rosbjerg

et al. 2014

Clim Dyn

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“…However, there are a number of reasons to question the quality of precipitation from coarse-resolution dynamical models, especially on hourly time scales. There can be large mean biases (Kjellström et al 2010), poor timing and durations , and incorrect spatial distributions (Gregersen et al 2013). One modeling study, that of Hanel and Buishand (2010), assessed hourly extremes simulated by the Ensemble-Based Predictions of Climate Changes and Their Impacts (ENSEMBLES) project 25-km parameterized-convection RCMs (Hewitt and Griggs 2004) over the Netherlands with the help of radar data, and found that the model-simulated generalized extremevalue distribution shape (location) parameters are too high (too low), leading to weaker short-return-period hourly extremes but overly intense long-return-period hourly extremes.…”

Section: Introductionmentioning

confidence: 99%

The Value of High-Resolution Met Office Regional Climate Models in the Simulation of Multihourly Precipitation Extremes

et al. 2014

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Extreme value theory is used as a diagnostic for two high-resolution (12-km parameterized convection and 1.5-km explicit convection) Met Office regional climate model (RCM) simulations. On subdaily time scales, the 12-km simulation has weaker June-August (JJA) short-return-period return levels than the 1.5-km RCM, yet the 12-km RCM has overly large high return levels. Comparisons with observations indicate that the 1.5-km RCM is more successful than the 12-km RCM in representing (multi)hourly JJA very extreme events. As accumulation periods increase toward daily time scales, the erroneous 12-km precipitation extremes become more comparable with the observations and the 1.5-km RCM. The 12-km RCM fails to capture the observed low sensitivity of the growth rate to accumulation period changes, which is successfully captured by the 1.5-km RCM. Both simulations have comparable December-February (DJF) extremes, but the DJF extremes are generally weaker than in JJA at daily or shorter time scales. Case studies indicate that ''gridpoint storms'' are one of the causes of unrealistic very extreme events in the 12-km RCM. Caution is needed in interpreting the realism of 12-km RCM JJA extremes, including short-return-period events, which have return values closer to observations. There is clear evidence that the 1.5-km RCM has a higher degree of realism than the 12-km RCM in the simulation of JJA extremes.

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“…To assert the considerable uncertainties associated with future projections of changes in the frequency and intensity of extreme events, such projections are generally based on multi-model ensembles (van der Linden and Mitchell, 2009) rather than single model projections, combined with different statistical downscaling methods (Gregersen et al, 2013;Sunyer et al, 2014). Design intensities and "climate factors" (i.e.…”

Section: Projections Of Extreme Precipitationmentioning

confidence: 99%

“…Design intensities and "climate factors" (i.e. the ratio between the expected future and present design rainfall) for extreme precipitation in Denmark under present and future conditions have previously been estimated from regional climate projections (Gregersen et al, 2013). Here we use recent results from the "RiskChange" project (Maule et al, 2014;Arnbjerg-Nielsen et al, 2015) to generate 15 different time series for design precipitation, each with a duration of 4 h and representing precipitation events from 5 to 100 year return values, using a Chicago Design Storm (CDS) rain calculator (IDA, 2014) (Table 1) for corresponding present-day and future climate conditions (2071-2100; RCP4.…”

Section: Projections Of Extreme Precipitationmentioning

confidence: 99%

Influence of urban land cover changes and climate change for the exposure of European cities to flooding during high-intensity precipitation

Kaspersen

Ravn²,

Arnbjerg‐Nielsen

et al. 2015

Proc. IAHS

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Abstract. The extent and location of impervious surfaces within urban areas due to past and present city development strongly affects the amount and velocity of run-off during high-intensity rainfall and consequently influences the exposure of cities towards flooding. The frequency and intensity of extreme rainfall are expected to increase in many places due to climate change and thus further exacerbate the risk of pluvial flooding. This paper presents a combined hydrological-hydrodynamic modelling and remote sensing approach suitable for examining the susceptibility of European cities to pluvial flooding owing to recent changes in urban land cover, under present and future climatic conditions. Estimated changes in impervious urban surfaces based on Landsat satellite imagery covering the period 1984-2014 are combined with regionally downscaled estimates of current and expected future rainfall extremes to enable 2-D overland flow simulations and flood hazard assessments. The methodology is evaluated for the Danish city of Odense. Results suggest that the past 30 years of urban development alone has increased the city's exposure to pluvial flooding by 6 % for 10-year rainfall up to 26 % for 100-year rainfall. Corresponding estimates for RCP4.5 and RCP8.5 climate change scenarios are in the order of 40 and 100 %, indicating that land cover changes within cities can play a central role for the cities' exposure to flooding and conversely also for their adaptation to a changed climate.

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Assessing future climatic changes of rainfall extremes at small spatio-temporal scales

Cited by 70 publications

References 24 publications

Long term variations of extreme rainfall in Denmark and southern Sweden

Long term variations of extreme rainfall in Denmark and southern Sweden

The Value of High-Resolution Met Office Regional Climate Models in the Simulation of Multihourly Precipitation Extremes

Influence of urban land cover changes and climate change for the exposure of European cities to flooding during high-intensity precipitation

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